Typically, for deposition of thin films on substrates the layer thickness of the deposited layer is of relevance. For many deposition processes deposition rate monitors are available. Signals of the deposition rate monitors and actually manufactured deposition rates can be correlated by a process called tooling, wherein a tooling factor is determined by the ratio of the deposited layer thickness and the rate measurement. This calibration might be particularly time consuming for deposition processes where a plurality of deposition sources and corresponding deposition rate measurements, each of which requires calibration, are provided. Applications with a particularly large number of deposition sources can be OLED manufacturing depositions.
Organic evaporators are an essential tool for the production of organic light-emitting diodes (OLED). OLEDs are a special type of light-emitting diodes in which the emissive layer comprises a thin-film of certain organic compounds. Such systems can be used in television screens, computer displays, portable system screens, and so on. OLEDs can also be used for general space illumination. The range of colors, brightness, and viewing angle possible with OLED displays are greater than those of traditional LCD displays because OLED pixels directly emit light and do not require a back light. Therefore, the energy consumption of OLED displays is considerably less than that of traditional LCD displays. Further, the fact that OLEDs can be manufactured onto flexible substrates opens the door to new applications such as roll-up displays or even displays embedded in clothing.
The functionality of an OLED depends on the coating thickness of the organic material. This thickness has to be within a predetermined range. In the production of OLEDs, it is therefore important that the coating rate, at which the coating with organic material is accomplished, lies within a predetermined tolerance range. In other words, the coating rate of an organic evaporator has to be controlled thoroughly in the production process.
Thereby, the deposition rate for OLED applications, but also for other deposition processes, needs to be controlled by a detector and the detector signal needs to be correlated with the thickness of the deposited layer. Accordingly, OLED deposition, but also all other deposition processes requiring a tooling between real deposition rate on a substrate and a signal of a rate measurement unit like oscillating quartz.
Typically, tooling is conducted by coating on one substrate and measuring the thickness after the coating in the coating machine or outside of the machine. This thickness can be transferred in a deposition rate and this is correlated to the signal of the measuring unit of the source. Typically, for each deposition source one substrate is used and coated with a standard carrier as used during production. Such a procedure—for a machine with many deposition sources (e.g. 10 or more sources for OLED applications)—requires a long time period because for each source a new substrate has to be handled one after the other.